1. Field of the Invention
The invention relates to an improved aluminium alloy and more particularly to an aluminium alloy which contains controlled amounts of defined compounds and is characterized by the combination of high extrudability and high corrosion resistance.
2. Description of the Prior Art
In the automotive industry, aluminium alloys are used in a number of applications, especially for tubing because of the extrudability of the alloys combined with relatively high strength and low weight.
Especially useful are aluminium alloys for use in heat exchangers or air conditioning condensers. In this application the alloy must have a good strength, a sufficient corrosion resistance and good extrudability.
A typical alloy used in this application is AA 3102. Typically this alloy contains approximately 0.43% by weight Fe, 0.12% by weight Si and 0.25% by weight Mn.
In W097/46726 there is described an aluminium alloy containing up to 0.03% by weight copper; between 0.05-0.12% by weight silicon, between 0.1 and 0.5% by weight manganese, between 0.03 and 0.30% by weight titanium between 0.06 and 1.0% weight zinc, less than 0.01% by weight of magnesium, up to 0.50% by weight iron, less than 0.01% by weight nickel and up to 0.50% by weight chromium.
In WO97146726 it is claimed that there is no positive effect of Cr on the corrosion resistance. It should also be noted that in the same patent, the lower level of manganese is 0.1% by weight.
There is a constant need for having aluminium alloys, having the combination of excellent extrudability and superior corrosion resistance. Excellent extrudability is required to minimize production costs at the extrusion plant, including lower extrusion pressure and higher extrusion speeds.